pull the 4.6 out buy the intake adapter plates and put a 5.4 back in. the junkyards around here are letting 5.4's go for only $290(u pull) and $371(they pull) after the intake adapter plates, the motor and some gaskets to "freshen up" the motor you've got less than a grand in the motor and have 50 extra cubic inches that will handle the same future mods as the 4.6